Cholesterol is a waxy substance that your body needs to build cells and manufacture vitamins and other hormones, according to the American Heart Association (AHA).

Your body makes all the cholesterol it needs in your liver. But you can also get cholesterol in the foods you eat. Dietary sources of cholesterol are primarily animal products and include:

Meat
Full-fat dairy
Poultry

These foods contain dietary cholesterol. But they also tend to be high in saturated and trans fat and trigger the liver to make more cholesterol. Other foods, such as palm oil, palm kernel oil, and coconut oil, contain saturated fat that can increase so-called “bad” cholesterol.

For some people, these foods represent a major source for increasing blood cholesterol. Because the typical Western diet is loaded with these foods, rising cholesterol levels have led the way to an epidemic of health problems linked to high cholesterol, says Trejo Gutierrez, MD, a cardiologist with the Mayo Clinic in Jacksonville, Florida.

Though some experts dispute the direct link between high blood cholesterol levels and cardiovascular disease (CVD), major organizations like the National Heart, Lung, and Blood Institute (NHLBI) maintain that high blood cholesterol levels play a role in the development of conditions such as atherosclerosis, carotid artery disease, coronary artery disease, heart attack, stroke, peripheral artery disease, and sudden cardiac arrest.

Types of Cholesterol and How They Work in Your Body

Cholesterol is carried through the circulatory system on two lipoproteins, particles made of both fat and proteins which transfer cholesterol from the bloodstream to the cells. This includes high-density lipoproteins (HDL), or “good” cholesterol, and low-density lipoproteins (LDL), also called “bad” cholesterol.

HDL cholesterol has been labeled “good” cholesterol because it removes some LDL cholesterol from the arteries and takes it to the liver, where it can be broken down and removed from the body, according to the AHA.

LDL is termed “bad” cholesterol because when there is too much of it circulating in the blood (more than the good HDL scavengers can scoop up and ferry away), it can eventually build up in the form of plaque on the walls of your arteries. This is called atherosclerosis. A research review published in the journal Cell states atherosclerosis starts with an accumulation of LDLs and some triglyceride-rich lipoproteins in the innermost layer of an artery. Over time, this narrows the arteries and raises the risk of heart attack, stroke, and peripheral artery disease, notes the AHA.

A high level of triglycerides — the most common type of fat in your body — can also lead to fatty buildups in your arteries and increase your risk of heart attack and stroke, if combined with high LDL or low HDL cholesterol levels, per the AHA.

Symptoms of High Cholesterol

Most people won’t know they have high cholesterol unless they get a blood test for cholesterol levels. This is because it is not common to have symptoms, unless you have very high levels of cholesterol. Symptoms include fatty bumps on your skin, most often on the elbows, joints, hands, feet or buttocks, and grayish-white rings around the corneas of the eyes. These symptoms typically occur in those with a family history of high cholesterol, according to the NHLBI.

Why Are Some People More Likely Than Others to Have High Cholesterol?

Understanding why some people have high cholesterol numbers and others don’t isn’t as simple as it might seem. For example, while overweight people are more likely to have high cholesterol, thin people can have it as well, notes the AHA.

Here are some factors that affect your cholesterol levels.

Heredity

A condition called familial hypercholesterolemia (FH) may make some people genetically prone to high levels of bad cholesterol. There are two types of FH: heterozygous, in which a person inherits the abnormal gene from one parent only; and homozygous, in which the person has two copies of the abnormal gene, one from each parent. Homozygous FH is both more rare and more dangerous.

People with FH don’t recycle LDL cholesterol as effectively and end up with high levels of this type of cholesterol, making them more prone to atherosclerosis, often starting at far younger ages. About 1 in 200 adults have the FH genetic mutation, according to the AHA. If left untreated, these individuals have a 20 times higher risk of developing heart disease.

If you have a parent, sibling, or child who has FH or who had a heart attack early in life, it’s recommended that you get tested for the condition. (The majority of FH patients need cholesterol-lowering drugs such as a statin to keep their cholesterol numbers in a healthy range.)

Smoking

While smoking doesn’t directly cause high cholesterol, it is by itself a major proven risk for heart disease and stroke. That risk rises if you also have high LDL cholesterol levels. One reason is that smoking lowers your levels of HDL, diminishing or erasing HDL's protective effect, according to the AHA.

Quitting smoking has immediate benefits on your heart health. A research review published in the journal Biomarker Research found that HDL levels increase almost immediately after a person quits smoking.

Diet

When it comes to what you eat, the best way to lower your cholesterol is to reduce your intake of saturated fat and trans fat, according to the AHA, which recommends limiting saturated fat to less than 6 percent of daily calories and minimizing the amount of trans fat you eat. This means cutting back on red meat, tropical oils, fried foods, and full-fat dairy. Additional guidelines published in the AHA journal Circulation in 2021 do not include a recommended intake of daily cholesterol; but the average consumption of Americans is around 300 milligrams (mg) per day. The authors recommend not going above this.

Instead, opt for low-fat or fat-free dairy products, fruits, vegetables, whole grains, poultry, fish, nuts, and nontropical vegetable oils. Healthier cooking oils include canola, corn, olive, peanut, safflower, soybean, sunflower, vegetable oil, and other specialty oils, notes the AHA. As a general rule, says Dr. Gutierrez, “consume a diet that is based mostly on whole, plant-based foods and is low in saturated and animal fats.”

Age

As we age, our metabolism changes, and our liver does not remove as much LDL cholesterol as it did when we were younger. Because of this, you may be at greater risk for high cholesterol as you age. High cholesterol is most commonly diagnosed in the 40–59 age group.

Race or Ethnicity

Non-Hispanic white people are more likely than other groups to have high levels of total cholesterol. Asian Americans are more likely to have high levels of LDL cholesterol than other groups. African Americans are more likely than other groups to have high levels of “good” HDL cholesterol, according to the NHLBI.

Sex

Research published in the AHA journal Circulation in 2019 has shown men to have a greater risk for high total cholesterol than women. This may occur because men report higher average intake of cholesterol than women.

A woman’s risk of high cholesterol goes up after menopause. During menopause, hormones that may protect against high blood cholesterol decline, leading to higher levels of LDL cholesterol and lower levels of HDL cholesterol, according to the NHLBI.

Getting Tested: What Do Blood Cholesterol Test Results Mean?

The AHA recommends that all Americans over age 20 get their cholesterol levels tested every four to six years, unless you have a medical history of heart disease or have risk factors for high cholesterol. Your doctor may recommend more frequent cholesterol tests in middle age, because that's when your overall risk of heart disease starts to rise.

Here’s what the test will reveal.

Total blood cholesterol Think of this as your overall "score." This number is the result of a calculation that adds up HDL and LDL levels, plus 20 percent of your triglyceride level, according to the AHA. Although stated guidelines point to a total cholesterol of below 200 milligrams per deciliter (mg/dL) as “desirable” and anything over 239 mg/dL as “high,” this number is less meaningful than it might appear, says Barbara Roberts, MD, a clinical associate professor emerita of medicine at Brown University in Providence, Rhode Island, and the former director of the Women’s Cardiac Center at the Miriam Hospital there. She adds that what’s important is the ratio of good to bad cholesterol.
HDL cholesterol You want this number to be higher, as a high HDL level is linked with good heart health. An HDL level of 60 mg/dL or higher appears to be protective against heart disease, notes the Cleveland Clinic. In contrast, a level of less than 40 mg/dL for males and under 50 mg/dL for women appears to be nonprotective and may be harmful.
LDL cholesterol An LDL of less than 100 mg/dL is the holy grail; a range of 100 to 159 mg/dL is borderline high, and above 159 mg/dL is in the danger zone, per the Cleveland Clinic.
Triglycerides Normal levels of triglycerides vary by age and sex, according to the AHA. Risk factors that can lead to high triglycerides include having diabetes, being overweight or obese, being sedentary, drinking alcohol in excess, and consuming a diet that is high in sugar, processed foods, and saturated fat. A normal level is below 150 mg/dL; if your level is approaching 200 mg/dL, that is mildly high; and anything over 200 mg/dL is moderately high, per the Cleveland Clinic. A triglyceride level of 500 mg/dL or higher is considered dangerously high and leaves you at increased risk for pancreatitis and cardiovascular disease.

Facts About Cholesterol-Lowering Medication

If you and your doctor feel lifestyle changes are not enough to lower your cholesterol levels, you may consider medications as the next plan of action. Guidelines put out by the AHA and the American College of Cardiology in 2019 say that the decision to start statin therapy should be based on a calculation of your risk for cardiovascular disease over 10 years. Elevated risk may occur in those with a history of cardiovascular disease and in adults age 40–75 with diabetes (See the risk calculator.)

Cholesterol numbers, says Gutierrez, are only part of the picture, “though the most current recommendations say that in the presence of diabetes you should start medication when LDL is higher than 70 mg/dL.”

He also points out that it’s important to first try making lifestyle changes, such as:

Consuming a healthier diet
Exercising
Quitting smoking
Getting blood pressure under control

It’s also important to note that those lifestyle changes should not be abandoned just because you’re taking medication.

Statin drugs work in two ways, says Gutierrez. “They block the enzyme that helps you produce cholesterol in the liver, and they activate the receptors for LDL in your liver cells, so that more cholesterol is ‘captured’ from your blood.”

In addition to statin drugs, a new class of cholesterol-lowering drugs called PCSK9 inhibitors was approved by the U.S. Food and Drug Administration (FDA) in 2015 to treat people with familial hypercholesterolemia and other risk factors. PCSK9 inhibitors are monoclonal antibodies that work to deactivate a protein in the liver called proprotein convertase subtilisin-kexin type 9 (PCSK9), reducing the amount of LDL circulating in your body.

Cholesterol and Heart Disease: Understanding the Connection

For years, it was believed that there’s more or less a straight line between cholesterol and heart disease — but research suggests that this relationship may be more complex.

A Minneapolis Heart Foundation study, published in April 2017 in the Journal of the American Heart Association, found that many people who have heart attacks don’t have high cholesterol. “The link between cholesterol and heart disease is weak,” says Dr. Roberts, who places a large portion of the blame for the persistence of that link on pharmaceutical advertising for statin drugs. “Statins do lower cholesterol levels,” she says, “but atherosclerosis still progresses” due to factors like age, poor diet, smoking, and so on.

In addition, a review of studies of cholesterol and cardiovascular disease published in the American Journal of Clinical Nutrition found that no rigorous connection could be drawn between dietary cholesterol intake and the risk of CVD.

In contrast, the results of long-term research, published in September 2017 in the journal Circulation, concluded that statin use in men with high LDL cholesterol who had no other risk factors for heart disease reduced their rates of coronary heart disease death, cardiovascular death, and all-cause mortality by 28 percent over 20 years.

Furthermore, a study of more than 400,000 people published in December 2019 in the Lancet found a strong link between non-HDL cholesterol and long-term risk of cardiovascular disease.

Still, when it comes to heart health, your biggest risk factor is age, says Roberts.

To keep your risk of high cholesterol as low as possible and your heart as healthy as you can for as long as you can, eat real (unprocessed) food, exercise regularly, don't smoke, and keep your blood pressure under control.

Additional reporting by Alexandria Jones-Patten, PhD, RN.